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Re: [PATCH 3/3] filemap: don't call generic_write_sync for -EIOCBQUEUED

To: xfs@xxxxxxxxxxx
Subject: Re: [PATCH 3/3] filemap: don't call generic_write_sync for -EIOCBQUEUED
From: Martin Steigerwald <Martin@xxxxxxxxxxxx>
Date: Sat, 28 Jan 2012 16:08:06 +0100
Cc: Jeff Moyer <jmoyer@xxxxxxxxxx>, linux-ext4@xxxxxxxxxxxxxxx, linux-fsdevel@xxxxxxxxxxxxxxx, linux-btrfs@xxxxxxxxxxxxxxx
In-reply-to: <1327698949-12616-4-git-send-email-jmoyer@xxxxxxxxxx>
References: <1327698949-12616-1-git-send-email-jmoyer@xxxxxxxxxx> <1327698949-12616-4-git-send-email-jmoyer@xxxxxxxxxx> (sfid-20120127_225408_201177_50791DCC)
User-agent: KMail/1.13.7 (Linux/3.2.0-1-amd64; KDE/4.7.4; x86_64; ; )
Adding linux-btrfs to Cc.

Am Freitag, 27. Januar 2012 schrieb Jeff Moyer:
> Hi,

Hi,
 
> As it stands, generic_file_aio_write will call into generic_write_sync
> when -EIOCBQUEUED is returned from __generic_file_aio_write. 
> EIOCBQUEUED indicates that an I/O was submitted but NOT completed. 
> Thus, we will flush the disk cache, potentially before the write(s)
> even make it to the disk!  Up until now, this has been the best we
> could do, as file systems didn't bother to flush the disk cache after
> an O_SYNC AIO+DIO write.  After applying the prior two patches to xfs
> and ext4, at least the major two file systems do the right thing.  So,
> let's go ahead and fix this backwards logic.

Would this need an adaption to BTRFS as well?

Thanks,
Martin

> Signed-off-by: Jeff Moyer <jmoyer@xxxxxxxxxx>
> ---
>  mm/filemap.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/mm/filemap.c b/mm/filemap.c
> index c4ee2e9..004442f 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -2634,7 +2634,7 @@ ssize_t generic_file_aio_write(struct kiocb
> *iocb, const struct iovec *iov, ret = __generic_file_aio_write(iocb,
> iov, nr_segs, &iocb->ki_pos); mutex_unlock(&inode->i_mutex);
> 
> -     if (ret > 0 || ret == -EIOCBQUEUED) {
> +     if (ret > 0) {
>               ssize_t err;
> 
>               err = generic_write_sync(file, pos, ret);


-- 
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
GPG: 03B0 0D6C 0040 0710 4AFA  B82F 991B EAAC A599 84C7

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